Process of treating hydrocarbon oil



H. V. ATWELL Filed Sept. 19, 1935 PROCESS OF TREATING HYDROCARBON OILNov. 23, 1937.

UM 'hw ATTO R N E-Y Passed Nev. 23,1937' UNITED STATES PATENT OFFICEaoaozo rnooEss oF raaillim mnooaaaon Harold v. Atwemwhne Plains, N. Y.,amor ewark,

Gasoline Products compania Inc., N

This invention relates to processes for the production oflight'products, such as gasoline, fro relatively heavy hydrocarbon oils.Y

It is an object of my invention to provide a process whereby relativelyheavy hydrocarbon oils may be converted into relatively high antiknockmotor fuel at high eiiiciency with minimized gas and other losses. Morespeciilcally it is an object of my invention to provide a process forcracking relatively heavy hydrocarbon oils to cause conversion thereofinto lighter products and to reconyert gas formed to liquid products lfalling within the desired boiling range, so that they may be blended inthe ilnal desired product. l5 In accordance with my invention freshcharging stock, such for example, as gas oil, is cracked underrelatively high temperature and moderately low pressure to produ'ce alarge percentage of gasoline per passagethrough the cracking zone -fwithout regard tothe amount ofincondensable gases produced at Itlriesame time. This step oiy the process is directed mainly to themaking,`by drastic vapor phase cracking, of large amounts of relativelyhighanti-knock value motor fuel in a single passage through a crackingzone. 'I'his conversion may be as high as 30|to 40% o'f products in thegasoline boiling range, per pass, or even higher. I'he resulting crackedproducts are separatedinto liquid residue, cycle stock, i. e. distillatestock of higher boiling point than that of the final desired product.liquid distillate of thev desired end point, and incondensable gases.The

gsaturates, particularly olefines, is then subjected to a polymerlzingaction adapted to cause conversion thereof into liquid productsfallingin the boiling range desired for the final product to beproduced, e.' g. gasoline, and the' polymerized products are separatedinto liquid residue, cycle stock, distillate of thedeslred'endpoint andincondensable gas. The liquid residue may be withdrawn from the processortreated in any con; ventional xnannemwhile the cycle stock is preferably returned wholly. or .in part, to the main 55 cracking zone-forfurther conversion. The dis- ,i ouate Iof the end point desired for thennal the cracking operation are preferably converted tillate ispreferably subjected to stabilization to remove therefrom undeslrablylight incondensable gases, and thesegases may be combined with theincondensable gases mentioned as separated from the polymerlzedproducts, and the mixture is 6 subjected to yrolysisunder conditionsadapted to produce liquid products falling in the desired boiling range.The resulting pyrolyzed p ucts are'separated into heavy tar, cycle sdisl0 product and incondensabl'e gas. The distillate may be conducted tothe,A blending zone rst mentioned and blended with the distillateproduced by the cracking operation and .that produced by thepolymerizing operation, or may be withdrawn from the system separately.Any two or more of the distillates produced may be blended as desired.The tar may bel withdrawn from the system in the usual manner. orsubjected-to any conventional treatment, while the cycle stockl ispreferably returned wholly orY in part, to the original crackingzone forfurther conversion of light products. 'I'his cycle stock is mainlyaromatic and a portion thereof may advantageously be combined with theincondensable gases resuit 25 ing from the cracking operation prio!` tothe poly- -merization thereof, so that reaction betweenV the cycle stockand the gasesundergolng polymerization will take place with attendantproduction of larger amounts of'light products in the' desired boilingrange than would fol ow from the treatment of either the cycle s or thegases alone. The gas separated from 4the pyrolyzed products, whichcontains substantial quantities of unsaturates such as olens and thelike. may also be combined with the-gases undergoing polymerization sothat conversion thereof into the final desired product results.

Inoperating according to the preceding description itis desirabletofractionate the cracked vapors totake overhead a distillate ofrelatively low end point, such for example. as 25,0 to @0 Il.

`This distillate neednot necessarily be sharply fractionated.Incondensable gases resulting to iiqulil by the polymeri'zins processmentioned, but other processes may be used if dired, to accomplish thisresult. For example, the gases N may be subjected to high temperaturepyrolysis, orhtiiey may b'e caused toreact with heavier oils 50 'suchVas pressure tar, tar distillate, orreilux condensate,l with or withoutthe oid of a catalystmmm The liquids thus produced are prafiiliiyl frac-1 tionated to yield a heavy naphtha of highantiknock value suitable forblending withjlie ,iight 55 neighborhood of` 2000 naphtha from theprimary operation to make specification motor fuel. f The abovementioned and further objects and advantages of my invention, and themanner of attaining them will be made clear in the follow.- ingdescription taken in conjunction with the accompanying drawing.

In the drawing reference numeral I indicates a charging lin'e throughwhich fresh charging stock, such as gas oil, for example M. C. gas oilof 35 A. P. I. gravity or any othersuitable clean hydrocarbon oiladapted for relatively drastic cracking without deleterious formation ofcoke, is introduced into cracking heater or furnace 2 under pressuregenerated by pump 3. The heater 2 is preferably of the tubular type andis adapted to raise the temperature of the oil passing therethrough toarelatively high value of, for example, 900 to 1100" F., preferably-950to 1000 F. thereabout, under a moderately lowpressure, e. g. in therange of atmospheric td 450 pounds per square inch or more, butpreferably about 200 pounds per sq. inch. During its passage through thecracking heater the oil undergoes relatively drastic cracking, sucientfor example, to cause conversion of 30-40 per cent thereof to productsin the gasoline boiling range, per passage. 'I'he highly heated crackedproducts pass from the cracking heater through transfer line 4, havingcontrol valve 5, into evaporator 6, wherein preferably substantially thesame pressure is 'malntained as at the outlet of the cracking heater,`

e. g. 200 pounds per square inch, but wherein a lower pressure may beused if desired. In the evaporator cracked products separate into vaporsand a liquid residue. The residue is drawn 01T from time to time orcontinuously through draw-'- 01T line 1, and may be diverted from thesystem or treated in any Well known manner, while the vapors passoverhead through vapor line 8 into fractionator tower 9. In thefractionator undesirably heavy fractions of the vapors are condensed asreflux condensate, and all or part of this condensate may be recycled tothe cracking heater'2, through lines I0 and II, any remainder beingdiverted from the process through line I2. Reference numeral I3indicates a reuxing line side the top of fractionator 9 in the usualmanner,

thereby regulating the boiling characteristics of' the vapors remaininguncondensed at the top of the tower. Vapors remaining uncondensed at thetop of the fractionator tower are withdrawn through vapor line I3' andcondenser I4, the resulting condensate being introduced into receiver orgas separating drum, I5. In this drum the incondensable gases separatefrom the condensate and these gases, which are relatively dry on ac-Acount of the pressure imposed thereon, may pass oi through vent line I6and line I1 to storage, but preferably pass through line I8. andcompresv sor I9 into polymerizing heater 20, in which they are subjectedto polymerization under a temperature of, for example, 800 to 1000" F.preferably about 900 F., and under a high pressure, which may be inexcess of 1000 lbs., for example, in the poundsgper square inch, more orless. In this ,Y of the gases undergo polymerization to liquids, some ofwhich fall within the boiling range of the final desired product. (Thepolymerized products pass oif from the heater20 through line 2 I, havingreducing valve 22, into evaporator 24, wherein sep- .aration thereofinto liquid residue and vapors takes place. As the polymerized productsleave supplied incooled upon leaving heater the oleilnic portion fthrough vapor line 48 from time to time, through line 26, and may beconducted to storage or treated in any Well known manner. The vaporspass overhead through vapor line 21, into fractionator tower 28, whereincondensation of undesirably heavy fractions takes place. Part or all ofthe reflux condensate formed in the fractionator may be diverted fromthe processv through lines 29 and 30, but preferably a substantial partor all of this reux condensate is recycled through line 3I underpressure generated by pump 32, to the cracking heater 2, for furtherconversion. Reference numeral 33 indicates al line through which acooling liquid may be supplied to the inside of the fractionator towerin the usual manner, to control the boil--l ing characteristics of thevapors remaining uncondensed at the top of the tower. 'I'he uncondensedvapors pass off from the top of tower 28 through vapor line 34, andcondenser 35, the 'resulting condensate being collected` in receiver orgas separator 36. In this receiver' incondensable gases separate fromthe condensed liquids and these gases may pass off from the separatorthrough vent line 31 and line 38 to storage, lbut preferably passthrough line 39 into pyrolyzing heater or yfurnace 40. under bycompressor 4I. K

In the heater 40, which is preferably of the tubular type, the gases aresubjected to pyrolysis by being raised to a relatively liigh temperatureunder low pressure and held at this high temperature for a relativelyshort period of time. 'I'he temperature to which the gas is heated maybe between about 1400D and 1800 F., preferably in the neighborhood of L0F., more or less, and the pressure may ,range from substantiallyatmospheric or lesa to as high as a hundred pounds, however relativelylow pressures are ordinarily preferable, and the time of contact mayvary from about one-tenth second to about ve seconds, more or less'. Inthis coil the gases, which are more ,or less paraflinic in nature, arepreferably largely reduced to liquid products, some of which inosphericvalue by mixing a diluent, such as steam or CO2, with the gases enteringthe furnace, valved pipe 4I' being provided for this purpose. Theproducts of pyrolysis pass from the heater 40, through line 42, int-oevaporator 43, being th'e heater by the mixture therewith of a quenchingoill introduced through line 44. This oil may be fresh charging stock orany other suitable material. In the evaporator 43 vapors separate fromliquid residue andthe latter is drawn 01T from time to time orcontinuously through pipe 45, either for diversion from the process, orfor any further treatment of a conventional nature. The vapors .passover-head through vapor line constituents, having a boiling point higherthan that desired for the final product, being separated out as reuxcondensate. The uncondensed vapors pass oi from the top of thefractionator and condenser 49, the resulting condensatebeing'collected'in gas separator or receiver 50. In this receiverincon'densapressure generated 46 into fractionator 41 andtherein undergopartial condensation, the heavier` ble gases separate from the liquidcondensate and these gases may be diverted from the process through pipe5I, but preferably are wholly or in part combined with the ga/sesintroduced into polymerizing heater 20, combination being brought aboutby the aid of conduit 52 having compressor 53, by means of which thegases from receiver 58 may be forced into pipe I8 leading to the heater20. Reflux condensate from the fractionator 41 may be wholly or partlydiverted from the process through pipes 5l and 55, but preferably thiscondensate is recycled through the system, a portion or al1 of it beingrecycled to cracking heater 2 through conduit 56. If desired a portionorali or this reflux condensate may instead be combined with the gasespassing through polymerizing heater 20, by diverting the condensatethrough the conduit 51, the desired control being eected by aid ofvalves 58 and 58. Distillate collecting in receiver 58, which fallswithin the boiling range cf the ilnal desired product, may be withdrawnfrom the process through line 80, b ut is preferably instead passedthrough line 6I and blended with distillate from receivers i5 and 36, oralternatively, distillate from any two of re- .ceivers 50, I5 and 38,may be blended to produce a desired product.

If desired the heater or furnace I0 may be so operated as to convert thegases passing therethrough into mainly unsaturated gases, such asolensbr the like, which are well adapted for polymerization in thepolymerizing heater 28, to

. which they may be conducted while hot, or after any desired degree ofquenching, through line 85 having control valve 88, and line 52, havingcompressor 53. Suitableunsaturatedgases from an external source may beintroduced to the heater 2l, through line 54' for treatment with gases/from separator I8, if desired, either with or without other adid gasesor liquids from the additional sources mentioned.

As shown on the drawing the distillates from receivers I5 and 38 aresubjected to stabilization to remove undesirably light gases therefrom.Distillate is withdrawn from receiverB I5 through line 62, heated, forexample by indirect heat exchange with hot products, e. g. tar or otherhot products of the process, in heat exchanger 83, and introduced intostabilizer tower 84, wherein stabilization is accomplished in the usualmanner, the undesirably light gases passing off from the top `of thestabilizer through line 85 and into line I8 leading to polymerizingheater 28 or being diverted wholly or in part from the process throughline 86. Reference numerals 81 and 81 indicate a pipe for introducingcooling liquid in the usual manner and a reboiler, respectively, tocontrol the operation of, the stabilizer. Stabilized distillate passesoil from the bottom of the stabilizer through conduit 88, and may beseparately withdrawn from the process through pipe 58. or instead passedthrough pipe 18 into line 8| which leads to receiving drum 1I, blendingwith the other distillates being accomplished in this man-` ner.Distillate from receiver 38 undergoes similar treatment in stabilizer12, being passed thereto through line 13.l The undesirably light gasespass oir from the top of the stabilizer through line 14 into conduit 38leading to heater I8, or part or all of these gases may be diverted fromthe process through pipe 15. Reference numeral 18 indicates aconventional refluxing line for controlling operation of the stabilizer.The stabilized distillate is withdrawn from the stabilizer tower throughpipe 11 and either separately withdrawn distillate from one or more ofthe other receivers.'

'I'he stabilizers 64 and 12 are preferably operated under substantiallythe same pressure as that of the fractionators 8' and 28, e. g. about200 pounds per square inch, butif desired the pressure used in thestabilizers may be increased by aid of pumps 80 and 8i in the two lines62 and 13 respectively. Where it is not desired to use stabilizers thepressures on the distillates in the receivers I5 and 36 may be reduced,either by operating the fractionators 8 and 28 at a, lower pressure orby reducing the pressure by aid of control valves 82 and 83respectively, thereby causing more o f the undesirably light vapors orgases to be removed from the distillate in the receivers I5 and 38leaving distillates having the desired freedom from light products. Whenit is not desired to use the stabilizers the distillates may bewithdrawn from the process either for individual use, or for blending,through lines 84 and 85.

In operation itis preferable to segregate in the receiver I5 of thecracking heater alight naphtha distillate of relatively low end pointwith respect to the final desired product. ordinary motor fuel is beingformed in the system the distillate in receiver I5 may have, forexample, an end point of 250 to 300 F. distillate will have a highanti-knock rating, having been produced by vapor phase cracking. It neednot necessarily be sharply fractionated. The heavier products necessaryto produce the nal desired blend may then be segregated in eitherreceiver or receiver 50 or both, being formed by polymerization and/orpyrolysis of the gases In the case where v resulting from the crackingoperation and -having a relativclyhigh anti-knock rating. 'I'hescdistillates or one of them is preferably so formed as to supply theheavy naphtha fractions decient in the distillate collected in receiverI5, the distillates then being blended to produce the final desiredproduct. The fractionator 28 is preferably operated at substantially thesame `pressure as that of fractionator 8, e. g. 200 pounds per squareinch, and may be operated at either higher or lower pressures as may bedesired to produce the desired distillate.

The specific values that I have mentioned hereinbefore are merelyillustrative of a specific set produce high anti-knock gasolinefractions,l

comprising mainly the lower boiling constituents of gasoline, with theattendant formation of relatively large quantities of incondensablegases, and

that these gases are subsequently treated to4 form high anti-knockproducts in the gasoline boiling range, it being preferable.. that thefinal product be produced by blending the distillate of. cracking withthat resulting from the conversion of the gases to liquids, the lattersupplying thenecessary heavy constituents. Various processes are knownfor converting gases to liquids in the gasoline boiling range, and thosewhich I have specically described hereinbefore are believed to bepreferable, but other processes may be used instead. It should be notedthat in the specific arrangement which I have-described in detail thegases are treated in two successive conversion steps, the result beingAthat the mainly olenic gases are first converted to liquids, andsubsequently the mainly=parafnic gases are converted to liquids. Insteadof following this procedure the gases could first be separated intoolenic and parafnic constituents by selective solvent action of naphtha,triethanolamine or similar solvent or in any other manner and eachseparate constituent subsequently subjected to the conversion processbest adapted to form therefrom the largest amount of liquid productsfall-- ring to one skilled in theart, may be made within the spirit ofthe invention as set forth in the appended claims. 5 v

I claim: I

1. The process of treating relatively heavy hydrocarbon oil for theproduction of gasoline which comprises subjecting said hydrocarbonl oilto a cracking operation to cause formation of `relatively highanti-'knock gasoline fractions,

separating from the'resulting cracked products distillate falling in thedesired boiling range but having an end point of from 250 to 300 F.,that is to say, an end point lower than that desired for the finalproduct, a condensate containing constituents boiling above 300 F. andwithin the upper portion of the boiling range of the desired product,heavier products and gas, returning at least a part of said condensateto the cracking operation Y for further treatment, subjecting said gasto heat and pressure to effect conversion of vconstituents thereof toliquid in the desired boiling rangeand heavier normally liquidhydrocarbons, recycling heavier normally liquid hydrocarbons thusobtained to the cracking operation to eiect drastic cracking thereof andblending liquid so formed with said gasoline fractions rst mentioned toform a final product having the desired boiling point range.

2. A process in accordance with claim 1 wherein unconverted gasesresulting from heat and pressure conversion of the gases are subjectedto high-temperature low-pressure conversion conditions for theproduction of additional liquid in the desired boiling range.

3. A process in accordance with claim 1 wherein unconverted gasesresulting from heat and pressure conversion of the gases are subjectedto elevated temperature to effect conversion of constituents thereof toliquid, i'ractionating the products of conversion to'separate liquid inthe vdesired. boiling range of the final product from heavier liquid andcombiningheavier liquid' thus obtained with gases' from the crackingoperation I prior to the subjection thereof to heat and pressure.

4. The process of producing gasoline from relatively'high-boiling oilwhich comprises cracking said oil under high temperature and lowpressure to produce a high yield of low-boiling products,

fractionatlng tie cracked vapors therebyprollquidhydrocarbons,separating the products of lconversion into a liquid hydrocarbon inthededuced toseparate a cracked gasoline distillate deficient inconstituents boiling above 2507F., ya.

higher-boiling condensate including constituents boiling immediatelyabove 300 F. and a lowerboiling fraction containing a relatively highpercentage of normally gaseous unsaturated constituents, subjecting saidhigher-boiling condensate to further cracking to produce lower-boilingproducts, the cracked vapors thereby produced being commingled withthose produced by the cracking of the high-boiling oil comprising theoriginal charging stock for fractionation, subjecting at least a portionof said lower-boiling fraction to elevated pressure and temperature fora suflicient period of time to effect polymerization of constituentsthereof to a normally liquid gasoline-like product lying within agasoline boilingpoint range and heavier normally liquid hydrocarbons,recycling heavier normally liquid hydrocarbons thus obtained to therelatively highboiling oil undergoing cracking to effect crackingthereof, and blending said product' with said cracked gasolinedistillate to form a balancedl gasoline product of high anti-knockvalue.

5. The process of treating relatively heavy hydrocarbon oil for thevproduction of gasoline, which comprises subjecting said relatively heavyoil to a high temperature cracking operation to cause drastic crackingthereof, separating the resulting cracked products into vapors and aliquid residue, forming from said vapors a distillate falling in theboiling range of the nal desired products but having an end point offrom 250 to 300 F., that is to say, an end point lower than that desiredfor th'e final product, and a condensate containing constituents boilingabove 300 F. and within) the upper yportion of the boiling range of thedesired product, and heavier, returning at least a vpart of saidcondensate to the cracking operation for further treatment, removingincondensable gases from the products of conversion, subjecting gasesthus obtained to elevated temperature and pressure to-eiectpolymerization of constituents thereof to a liquid distillate falling inthe boiling range of the nal desired product and having an end pointcorresponding to that of the nal desired product an'd heavier normallyliquid hydrocarbons, recycling heavier normally liquid hydrocarbons thusobtained to the cracking operation to. effect drastic cracking thereof,and blending the rst and second mentioned distillates to form the finaldesired product.

6. A process in accordance' with claim 5 wherein said liquid distillatesecond-mentioned consists predominantly of the heavier gasolinefractions necessary to supply the deficiency thereof in the distillatefirst-mentioned.

7. The process of treating relatively heavy hydrocarbon oil for theproduction of gasoline which comprises subjecting said hydrocarbon oilto a cracking operation to cause formation of relatively high.anti-knock gasline fractions, separating from the. resulting crackedproducts distillate falling in the desired boiling range but having vanend point of from 250 to 300 F., that is to say,` an end point lowerthan that desired for the final/product, a condensate containingconstituents boilingV above 300 F. and within the upper portion of theboiling range of the de-` conversion of. constituents thereofto normallyucts of conversion to separaige liquid in the desired 4boiling range ofthe nal product from heavier liquid and combining heavier liquid thusobtained with gases from the cracking operation prior to the subjectionthereof to heat and pres- 5 sure.

HAROLD V. ATWELL.

